Sensitive relay device



Sept. 17, 1935. A. H. LAMB SENSITIVE RELAY DEVICE Filed July 11, 1934 Patented Sept. 17, 1935 UNITED STATES SENSITIVE RELAY DEVICE Anthony H. Lamb, Elizabeth, N. J., assignor to Weston Electrical Instrument Corporation, Newark, N. J a corporation of New Jersey Application July 11, 1934, Serial No. 734,679

9 Claims.

ment contacts.

Almost without exception, any set of sensitive instrument contacts functioning to make and then break a load circuit can readily handle higher values of current and voltage when making contact than when breaking contact. This is particularly true of instrument contacts included in an inductive load circuit asf upon opening the circuit, the contacts are subjected to an inductive discharge during which the voltage across the instrument'contacts may rise to the order of a hundred or more times the normal load voltage. I have described and claimed highly sensitive relay devices of the instrument type in my copending application Serial'No. 688,696, filed September 8, 1933, such instruments including a contact arm carrying a contact in the form of a magnetic rider for cooperation with a stationary contact constituted by a small permanent magnet, and a pusher arm for separating the contacts after the contact engagement has performed its intended function. According to one application of that invention, the instrument contacts may be a switch or series elements inthe load circuit, as illustrated in Figs. 4 and 7 of the said application,

and the intended function of the instrument contacts in such case is to act as the make-and-break control switch in the load circuit.

The present invention contemplates sensitive instrument type relays such as described in my prior application, and objects of the invention are to provide an instrument relay of simple construction and in which the limiting values of current and voltage which may be safely handled by the relay are determined by the values which may be handled upon a closure of the relay contacts and are substantially independent of the characteristics of the load circuit. A further object is to provide a sensitive relay instrument of the magnetic pull-in type which includes a pusher arm for separating contacts that are drawn into engagement by magnetic attraction, and in which additional switch contacts capable of handling relatively high currents and voltages are arranged in series with the instrument contacts, the additional switch being controlled by the movement of the pusher arm.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing, in which:

Fig. 1 is a diagrammatic view illustrative of the invention;

Fig. 2 is a fragmentary plan view of the invention as embodied in a relay of the electrical measuring instrument type; 5

Fig. 3 is a sectional view of the same taken substantially on line 3-3 of Fig. 2;

Fig. 4 is a fragmentary plan view of the same, but showing the pusher arm displaced to separate the instrument contacts andthe auxiliary contacts; 10 I Fig. 5 is a sectional detail view looking in the direction indicated by the dotted line arrow 5 of Fig. 4, of the pusher arm and associated parts of the instruments; and

Fig. 6 is a fragmentary sectional view of the 15 magnet contact and its insulated mounting.

For purposes of illustration, I have shown the invention as embodied in an electrically operated relay including a field structure indicated by the magnetic poles I, and a moving system including zo the coil 2 and a contact arm 3, but it is to be understood that the moving system which actuates the contact arm may respond to other factors, such as temperature, pressure, humidity and the like. As described in my prior application, 25 the contact arm carries a small rider 4 of magnetic material, such as soft iron, for cooperation with a relatively fixed contact 5 that takes the form of a small permanent magnet. These contacts are series elements, 1. e., a switch, in a load circuit which is shown schematically as including a load 6 and a source of current I.

The magnetic contact elements insure a reliable contact engagement as soon as the changing value of the measured factor reaches that value which brings themagnetic rider 4 within a predetermined distance from the magnet 5. The instrument contacts are not separated by the force established by the moving system but, as described in my prior application, by a pusher arm 8 which carries a short rod or pin 9 for forcing the con tact arm 3 and rider 4 away from the contact magnet 5.

The construction, asso far described, is substantially that which is illustrated in my prior46 application and the maximum current which may be controlled by the stated elements is determined by the values of current and voltage which are handled by the instrument contacts when they are separated. The contacts may be plated with gold 50 or other metal of high conductivity but, in general, the current flow which may be safely handled upon a closure of the instrument contacts is of an order substantially higher than that which may be handled when the contacts are separated. 66

, the left edge of In accordance with the present invention, the function of breaking the load circuit is not performed by the instrument contacts but by an auxiliary set of switch contacts I II, II which are so controlled by the pusher arm that the auxiliary switch is opened before the instrument contacts 4, 5 are separated. The auxiliary switch is also a series element in the load circuit and, as shown diagrammaticallyin Fig. 1, the switch contact ll may be mounted directly upon the pusher arm to cooperate with a; fixed switch contact l which is so positioned that the contacts In, II open before the pin 9 of pusher arm 8 separates the instrument contacts 4, 5. The auxiliary switch is suitably designed to handle currents and voltages which are many times greater than those which could be handled by the delicate instrument contacts.

The small space required fora highly sensitive relay instrument capable of handling rela-- tively high values of current and voltage is indicated by Figs. 2 to 6 which illustrate, on a somewhat enlarged scale, one appropriate construction of a sensitive relay merit type, In actual practice, the instrument may be of the milliammeter type such as is commonly housed in a casing of about 2 inches in diameter and 1 inches in height.

So far as appropriate, the reference numerals of Fig. 1 identify corresponding parts of the physical structure shown in Figs. 2 to 6, inclusive. Current flow in coil 2 displaces the contact arm or pointer 3 over the scale plate I! and, in the particular construction illustrated, the magnetic rider 4 is attracted'to the contact magnet 5 (as indicated in dotted lines) when the current flow reaches that value which brings the pointer 3 to the scale, i. e., to the position shown in solid lines in Fig. 2. Movement of the pointer in the opposite direction is restricted, as

is common practice, by a stop H which is carried by a spring arm I. mounted upon, butinsulated from, a bracket l5 to which the relatively stationary contact I i of the auxiliary switch is secured. The contact in may be a flexible strip. such as used in the telephone lack type of switch. which is secured to the con-, tact magnet 5. The contacts III, II are normally held in engagement by the pin 9 which is mounted on one end of the pivoted pusher arm I, the pusher arm 8 being urged in a clockwise direction, as viewed in Fig. 2, by the torsion spring IS. The pusher arm 8 is preferably formed of molded insulating material with a hub 8' which is pivotally mounted on a shaft I! which, in turn, is pivoted in a bushing I8 carried by the instrument base l9, and the outer end of the shaft lever arm 20 for rocking the shaft A crank arm 2| is fixed to the shaft l1 and has a flange engaging a projection on the extension 22 ing movement of the shaft to the pusher arm. The extension 22 carries a pin 23 which is received within the fork of a crank arm 24 on the manually operable shaft 25 that extends through the glass cover plate 26 of the instrument.

It will be apparent that a counterclockwise movement of the pusher arm may result from a manual actuation of the shaft 25 or from a manual or automatic actuation of the lever 20 through mechanism, not shown, which is energized by the closure of the instrument contacts; one form of such mechanism being illustrated and described of the electrical instru- The contact magnet 5 is amines is opened at the auxiliary switch III, II. In- 5 strument relays embodying this invention may therefore be employed to control any load circuit in which the current flow may be safely established by a closure of the instrument contacts whether or not that current flow and/or the nature of the load circuit are such that the instrument contacts could not be relied upon,to break the load circuit.

The drawing does not illustrate the load circuit in detail, since it will be apparent that different types of load circuits may be controlled by any one instrument relay. The load circuit may include the particular electrical element, device or circuit which is to be controlled, or it may comprise an auxiliary relay which, in turn, controls some other element or circuit.

It will be apparent that the invention is not restricted to relays of the electrically actuated type or to the particular construction herein illustrated and described, as various changes which will occur to those familiar with the design and construction of relay instruments fall within the spirit of my invention as set forth in the following claims.

I claim: 30

1. A relay for controlling an electric circit, said relay comprisingamoving systemincluding a contact of magnetic material, a relatively stationary contact cooperating with said first contact and comprising a magnetized body, a normally closed auxiliary switch having contacts adapted to be connected in series with said magnetic contacts, and means operable to open said auxiliary switch and thereafter to separate said magnetic contacts, whereby the circuit which is closed by the engagement of said magnetic contacts is broken by the auxiliary switch.

2. A relay comprising a base, a moving system carried by said base, a contact on said moving system cooperating with a relatively stationary contact to constitute a switch adapted to be included in a load circuit, an auxiliary switch having contacts adapted to break a heavier current flow than can be handled by the first pair 01' contacts, a pusher arm movably mounted on said base to control both switches, and means yieldingly retaining said pusher arm in normal position to close the auxiliary switch and to permit free movement of the moving system and the contact carried thereby, said pusher arm being movable from said normal position to open said auxiliary switch and thereafter to force the contact of the movable system away from its cooperating stationary contact.

3. A relay as claimed in claim 2, wherein said moving system contact and cooperating contact are magnetic.

4. A relay as claimed in claim 2, wherein said moving system contact is of magnetic material and the cooperating stationary contact is a magnetized body.

5. A relay comprising a base, a moving system carried by the base, a contact of magnetic material on the moving system and cooperating with a relatively stationary magnetized contact, an insulating support for said magnetized contact, an auxiliary switch having a contact electrically connected to said magnetized contact and cooperating with a second switch contact, means controlling said auxiliary switch and the range of movea,o14,ass 3 ment or the contact on the movable system, said means including a pusher arm movable into the path or movement of the movable system to force the movable system contact away from the co 5 operating stationary contact, and spring means normally retaining the pusher arm outside the path of movement of the movable system and in position to hold said auxiliary switch closed.

6. In a relay, the combination with a measur- 1 mg instrument including a moving contact of 7. An instrument relay comprising a housing including, a base and a cover, a moving system mounted on said base and carrying a pointer, a magnetic contact on said pointer, a relatively sta- 26 tionar'y magnetized contact, means mounted on said base for rocking movement to separate said contacts, means yieldingly retaining said separatin: means in a normal position which permits free movement of said moving system and pointer. a switch biased towards open position and retained in closed position by said separating means when the latter occupies its said normal position,

and adjustable means operable from the exterior 5' of said housing to rock said separating means to open said switch and thereafter to separate said contacts. I

8. An instrument relay as claimed in claim 7, wherein said separating means includes a piv- 1o otally mounted arm carrying a pin for alternative engagement with said switch or with said pointer, and said adjustable means includes a crank arm on a shaft adjustable from the exterior of the housing, said crank arm being adapted to turn 15 said pivotally mounted arm in opposition to the force exerted by said yielding retaining means.

9. An instrument relay as claimed in claim 7, wherein said separating means includes a pivotally mounted 'arm carrying a pin for alterna- 20 tive engagement with said switch or with said pointer, and said adjustable means includes a pair of crank arms alternatively operable to rock said pivotally mounted arm, and shafts carrying respective crank arms andpivotaily mounted on 98 said base and said cover, respectively.

ANTHONY n. 

